1. Field
An optical sensor is provided.
2. Discussion of the Background
Flat panel displays such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, and an electrophoretic display include plural pairs of field generating electrodes and an electro-optical active layer interposed therebetween. The liquid crystal display includes a liquid crystal layer as the electro-optical active layer and the organic light emitting diode display includes an organic emission layer as the electro-optical active layer. One of the field generating electrodes constituting one pair is generally connected to a switching element to receive an electrical signal and the electro-optical active layer converts the electrical signal into an optical signal to display an image.
In recent years, the display may include a touch sensing function which can interact with a user in addition to the function of displaying the image. In the touch sensing function, when a user writes characters or draw figures by touching a screen with a tool such as a finger or a touch pen, the display senses changes such as pressure or light applied to the screen to find whether there is a touch in the screen and information about a touch position. For example, in order to implement the touch sensing function, an infrared light sensing transistor may be used.
The display may also include an image sensing function. The image sensing function is to recognize images such as photographs and bar codes. For example, in order to implement the image sensing function, a visible light sensing transistor may be used.